Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
h,w = map(int,input().split())
s = [input() for i in range(h)]

ex = [[0] * w for i in range(h)]

ex[0][0] = 1
do = [[0,0]]
check = [[1,0],[-1,0],[0,1],[0,-1]]

white = 0
for i in s:
  white += i.count('.')




while(len(do)!=0):
  x,y = do.pop(0)

  
  for i,j in check:
    a = x + i
    b = y + j
    if(-1<a<h and -1<b<w):
      if(a == h-1 and b == w-1):
        print(white-(ex[x][y])-1)
        exit()
      elif(ex[a][b] == 0 and s[a][b] =='.'):
        ex[a][b] = ex[x][y] +1
        do.append([a,b])
print(-1)